The Battle of Berestechko was fought from 28 June to 10 July 1651 during the Khmelnytsky Uprising when the combined armies of the Cossack Hetmanate and Crimean Khanate were crushed by Poland-Lithuania's army on the hilly plain south of the Styr River in Volhynia.
In one of the largest land battles of the 17th century, 33,000 Cossacks, 30,000 Crimean Tatars, 2,000 Don Cossacks, and thousands more peasants, Turks, and Vlachs faced off against 17,000 Polish cavalry, 16,000 infantry, and 56,000 mobilized nobles and peasants. Among the Polish soldiers were 2,250 German-style cavalry, 11,900 German-style infantry and dragoons, 2,950 Hungarian-style infantry, 1,550 Lithuanian volunteers, and 960 Lipka Tatars; a large number of Registered Cossacks remained loyal to Poland.
On the first day of the battle, 2,000 Polish cavalry repulsed an attack by Crimean Tatars, inflicting heavy losses. On the second day, the Poles deployed all their available cavalry against the main Tatar horde and Cossack vanguard regiments. This time, the Polish cavalry - unsupported by infantry and artillery - were pushed back to their camp but were then repelled by Polish infantry and artillery. The Crimean general Tugay Bey was among the slain. On the third day of battle, the Crown Army attacked the Cossack-Tatar camp before being pushed back. The Polish left began to retreat before the King turned the tide by deploying German mercenaries. Rainfall forced the Poles to retreat. The two sides exchanged artillery fire for ten days while both sides built fortifications. The Cossacks' morale decreased as desertions began, and, on the morning of 10 July, the Cossack Ivan Bohun led a desperate cavalry charge against the Poles. The Cossack peasants, who were uninformed of the attack, feared that they were abandoned and retreated. Bohun failed to restore order on returning to the camp, and the Poles pursued the disorganized mob. A rearguard of 300 Cossacks fought to the last man, and the Poles captured Bohdan Khmelnytsky's tent intact. The retreating Cossacks lost most of their artillery to the Poles or the marshes during their retreat. King Jan Casimir failed to press the pursuit of the fleeing Cossacks, as rainy weather, a lack of food and fodder, the spread of diseases, and the unwillingness of the nobility to proceed into Ukraine immobilized his army. After the inconclusive Battle of Bila Tserkva that same year, the Poles and the rebels made peace on 28 September 1651, and Poland reduced the number of registered Cossacks from 40,000 to 20,000 and deprived them of the right to settle in or control various provinces of Ukraine previously promised to them. As a result, the uprising would continue until Khmelnytsky's death in 1657.